Syringes for making precision volume measurements

ABSTRACT

A syringe comprising a barrel, a main bore in the barrel opening at one end thereof, a needle receiving bore in the other end of the barrel substantially coaxial with the main bore and communicating therewith, a hollow needle removably engaged in the needle receiving bore, a syringe plunger extending through the main bore and the needle receiving bore to precisely engage within the hollow needle, sealing means in said needle receiving bore and including a resilient seal through which the plunger slidably moves, and means holding the needle in the needle receiving bore with the inner end of the needle in sealing engagement with said resilient seal.

United States Patent Dawes 1 1 NOV. 25, 1975 SYRINGES FOR MAKING PRECISION VOLUME MEASUREMENTS [76] Inventor: Ernest Frederick Dawes, 99 Kilby Road, East Kew Victoria. Australia [22] Filed: Sept. 20, 1973 [21] App1.No.:399,344

[30] Foreign Application Priority Data Sept. 22. 1972 Australia. 533/72 [52] US. Cl. .4 222/386: 128/218 P; 222/309 [51] Int. A61M 5/315; A61M 5/34 [58] Field of Search 222/309 386'. 128/218 C. 128/218 P, 218 PA, 221

[56] References Cited UNITED STATES PATENTS 1,403,021) 1/1922 Everett. 128/221 2.739.589 3/1956 Yochem i i i i i i i H 128/218 C 3,2l6 616 11/1965 Blankenship t i i t t h 222/386 3,401.692 9/1968 Harrisu i i 128/218 C $677,448 7/1972 Harris i 1 v v v v i i v t 1 128/218 C 3.811790 6/1974 Allen 222/386 Primary Examiner-Robert B. Reeves Assistant ExaminerThomas E. Kocovsky Attorney, Agent, or FirmCushman. Darby & Cushman [57[ ABSTRACT A syringe comprising a barrel. :1 main bore in the bar rel opening at one end thereof. a needle receiving bore in the other end of the barrel substantially coaxiai with the main bore and communicating therewith a hollow needle removably engaged in the needle receiving bore a syringe plunger extending through the main bore and the needle receiving bore to precisely engage within the hollow needle, sealing means in said needle receiving bore and including a resilient seal through which the plunger slidably moves and means holding the needle in the needle receiving bore with the inner end of the needle in sealing engagement with said resilient seal.

7 Claims, 4 Drawing Figures SYRINGES FOR MAKING PRECISION VOLUME MEASUREMENTS BACKGROUND OF THE INVENTION This invention relates to improvements in syringes and relates particularly to an improved measuring syringe.

Heretofor, measuring syringes have been developed to inject minute samples in gas chromatography, for delicate medical injections, in treatment of animals, and for a number of uses in laboratory work. Such syringes may have a maximum capacity of ten microliters although syringes of this type are known with much larger and much smaller capacities. These syringes are generally formed with an axially bored cylindrical glass barrel having a needle at one end and a plunger within the barrel for injecting material therein through the needle. The barrel is provided with graduations for accurate measurement of injected amounts.

Syringes have been proposed with removable needles whereby a needle which has become bent or blocked through use may be quickly and simply replaced. However, syringes fitted with replaceable needles have generally been unsuitable for use in applications involving injections under a high pressure in view of the difficulties of maintaining a seal between the needle and the barrel.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved construction of syringe which overcomes the above mentioned disadvantages.

A still further object of the invention is to provide an improved construction of syringe having means to facilitate multiple delivery of identical quantities of liquid.

A still further object of the invention is to provide a syringe having an improved construction of needle to facilitate insertion of the needle into a septum, or the like, without damage thereto.

It is another object to provide a syringe having a replaceable needle wherein the syringe plunger precisely fits into the needle for the purpose of ejecting minute quantities of fluid (liquid or gas) therefrom.

It is another object to provide a syringe having a seal between the needle, barrel and plunger which is effective at high pressures (up to about 10,000 p.s.i.).

It is another object to provide a high pressure syringe having a seal assembly which remains effective over an extended period of use of the syringe.

It is another object of the invention to provide a syringe wherein the seal between the needle, barrel and plunger is relatively simple in construction and is easy to replace if needed.

According to the invention there is provided a syringe comprising a barrel, a main bore in the barrel opening at one end therof, a needle receiving bore in the other end of the barrel substantially coaxial with the main bore and communicating therewith, a hollow needle removably engaged in the needle receiving bore. a syringe plunger extending through the main bore and the needle receiving bore to precisely engage within the hollow needle, sealing means in said needle receiving bore and including a resilient seal through which the plunger slidably moves, and means holding the needle in the needle receiving bore with the inner end of the needle in sealing engagement with said resilient seal. I

In one preferred arrangement. the means holding the needle comprises a threaded boss on the end of the bar-- rel, an internally threaded nut engaged with the boss, the nut having an aperture through which the needle extends, shoulder means on the needle and resilient means acting between the nut and the shoulder means to resiliently urge the needle into sealing engagement with the seal.

The plunger, which has a relatively small diameter (the total capacity of the syringe may be only 0.5 microliters and the plunger may have an axial movement of about 3 centimeters is preferably supported and guided in its axial movement through the barrel by a support tube secured in the barrel. The support tube acts to prevent bending and kinking of the fine plunger.

A further outer tube or sleeve may be axially movable in the main bore of the barrel to provide a visual indication. in conjunction with graduations marked on the barrel surface, of the volume of the syringe at any position of the plunger. Further, this outer tube or sleeve engages with the inner end of the bore to limit inward movement of the plunger at the zero end of the plunger movement.

The seal is preferably formed of an unsintered polytetrafluoroethylene which, under the action of the resilient means holding the needle against the seal, l'lows to seal against the end of the needle, the barrel and the plunger. The pressure constantly applied to the seal ensures that continued operation of the syringe plunger does not result in gradual development of leakages.

In syringes of relatively large capacities of the order of 25 microliters, the needle diameter is relatively large. To avoid damage to septums. delicate membranes and the like through which the needle must be inserted in use of the syringe, the invention provides a needle having an entering end, or probiscus, of reduced diameter. The probiscus has a relatively small diameter bore which reduces the likelihood of damaging membranes, septums and the like during insertion of the needle.

The invention also provides a syringe comprising a barrel, a bore in the barrel opening at one end thereof, a needle engaged in the other end of the barrel and communicating with the bore, a plunger slidably mounted in the bore, an operating button on the outer end of the plunger, an annular resilient sealing member disposed between the barrel and a sealing surface on the needle, fastening means on the barrel and engaged with the needle to hold the needle in sealing engagement with the seal, and a repetitive delivery assembly on the barrel and connected to the plunger. the assembly including a member adjustably clamped to the outer surface of the barrel, elongated rod means extending through a hole in the member parallel with the axis of the bore, means connecting the outer end of the rod means to the plunger for axial movement therewith, and shoulder on the other end of the rod means engageable with the member to limit outward move ment of the plunger.

The repetitive delivery assembly enables repeated operations of the syringe to deliver in each operation an identical volume of fluid without the necessity of relying on a visual indication each time.

DESCRIPTION OF THE DRAWINGS In order that the invention will be more fully understood several embodiments thereof will now be described with reference to the accompanying drawings,

3 wherein:-

FIG. 1 is a cross sectional side elevational view of a syringe according to the present invention,

FIG. 2 is a cross-sectional view of a modified form of syringe,

FIG. 3 shows a further modified form of syringe, and

FIG. 4 is a detailed sectional view showing an alternative construction of needle for use with a syringe of the invention.

Referring to FIG. 1 of the drawings, the syringe. indicated generally at 11, comprises a cylindrical glass barrel 12 having an axial bore 13 open at one end 14 of the barrel ]2. The other end of the bore 13 communicates with bore 16 of lesser diameter than the bore 13, the bore 16 being open at the opposite end 17 of the barrel 12.

The end 17 of the barrel [2 is of reduced outer diameter and a threaded boss 18 is secured thereon.

A plunger guide tube 21 is secured in the bore 16 and extends towards the end 14 substantially coaxially of the bore 13. The end of the plunger guide tube in the bore 16 forms a shoulder 22 for the end of a needle 23 engaged in the bore l6. The needle 23 has a shoulder 26 secured thereto and a nut 27 adapted to engage on the boss 18 compresses a spring 28 against the shoulder 26 to resiliently secure the needle 23 in the bore 16.

A plunger 31 extends from a finger piece 32 to slidably engage in the plunger guide tube 21. The plunger 31 and plunger guide tube 21 are constrained to a coaxial position relative to the bore 13 by a supporting tube 33 secured to the finger piece 32.

The free end of the supporting tube 33 is also arranged to engage the end of the bore 13 to limit inward movement of the plunger. Further. the barrel 12 may be provided with graduations and the movement of the end of the tube 33 gives a visual indication of the plunger movement and contents of the syringe.

The plunger 31 extends into the needle bore 34 which forms the barrel therefor. Extremely close toler' ances are provided between the plunger 31 and the needle bore 34 to ensure the maximum possible accuracy in liquid delivery.

Leakage of liquid from the needle is substantially prevented by an annular seal between the shoulder 22 and the end of the needle. The seal 20 is preferably formed of polytetrafluoroethylene either sintered or unsintered and it is compressed between the respective parts by the compression spring 28 acting on the needle. The resilience of the seal results in complete sealing against the plunger surface and against the wall of the bore 16 as well as against the end of the needle 23.

Referring to FIG. 2, there is illustrated a modification of the construction of syringe shown in FIG. 1. With the modified construction the diameter of the plunger 31 is relatively less than that of FIG. I. To avoid having.

therefore. a relatively long. fine plunger 31, the plunger guide 36 extending from the finger piece (not shown) is of larger diameter to obviate any tendency to bend or kink. The guide 36 tapers down into the plunger 31 which extends into the needle as previously described.

The plunger guide tube 21 is of a diameter to receive the plunger guide 36. The plunger guide 36 may be formed by securing a tube by one end thereof to the plunger 31, the tube having an internal diameter to receive the plunger 31 and an external diameter to engage within the plunger guide tube 21. Thus the plunger guide 36 acts purely as reinforcing for the fine plunger 31.

Referring to FIG. 3, this syringe comprises a cylindical glass barrel 12 with an axial bore 13. A needle bore 13 extends towards the inner end of the bore 13 from one end of the barrel [2 and the two bores 13 and 30 communicate by means of a thirdbore 41.

A needle 23 is resiliently secured in the needle bore 40 as previously described.

In this embodiment. the plunger 31 is secured to the free end of a plunger guide 42 which is coaxial with the bore 13. The plunger 31 extends through the third bore 41, through a resilient seal 40 into the needle bore 34.

The seal 40 is compressed between the end of the needle 23 and a shoulder 43 formed between the end of the needle bore 30 and the third bore 41. The shoulder 43 may be of tapered form. as illustrated. or it may be substantially perpendicular to the barrel axis.

The plunger guide 42 which slides within the bore 13 provides the desired indication. in conjunction with graduations marked on the barrel. of delivered quantities of liquid. Further. the end of the bore 13 acts as a stop for the guide 42 to limit movement of the plunger 31 in the needle.

In certain uses of the syringe. it is necessary to deliver a number of identical measures of liquid. For this purpose, the syringe is provided with an adjustable stop 46 which is formed in two parts and clamped to the syringe barrel 12. The stop 46 may be adjustably moved along the barrel and fastened thereto in any suitable position. The stop 46 is provided with a bore 47 therethrough which is substantially parallel with the barrel axis. A rod 48 is slidably mounted within the bore 47, the rod having one end thereof bent at right angles. as at 49, and adapted to engage in a transverse hole 51 formed in the syringe operating button 52 on the outer end of the plunger 31. The other end of the rod 48 is formed with a shoulder 53 to limit outward movement of the rod 48 in the bore 47. The stop 46 may be shaped with finger-engaging recesses 54 to facilitate use of the syringe.

In use, the stop 46 is clamped on the barrel 12 at the location to limit outward movement of the plunger to give the desired measurement of liquid to be delivered. The outward movement of the plunger 31 in the syringe is limited by engagement of the shoulder 53 with the stop 46.

A number of deliveries may now be made and an identical amount of liquid will be delivered on each operation of the syringe. The syringe may be dismantled by simply disconnecting the rod 48 from the hole 5] in the button.

As the syringe illustrated in Fig. 3 has a relatively large diameter plunger this syringe has a capacity of up to 25 microliters with graduations of 0.5 microliters the needle must therefore be of correspondingly large diameter. Such a large diameter needle has a large point and may tend to damage delicate membranes, septums and the like through which the needle must be passed.

To overcome this problem. the outer or entering end 61 of the needle is reduced to a diameter substantially less than that of the inner end of the needle, as illustrated in FIG. 4. The entering end 61 may be electrolytically tapered and then ground to provide a relatively fine point with a reduced diameter bore 63. The needle length is arranged so that the end of the plunger 31 stops at the reduced diameter probiscus 61.

I claim:

l. A syringe comprising a barrel. a main bore in the barrel opening at one end thereof, a needle receiving bore in the other end of the barrel substantially coaxial with the main bore and communicating therewith. a hollow needle removably engaged in the needle receiving bore, a syringe plunger extending through the main bore and the needle receiving bore to precisely engage within the hollow needle, sealing means in said needle receiving bore and including a resilient seal through which the plunger slidably moves, and means holding the needle in the needle receiving bore with the inner end of the needle in sealing engagement with said resilient seal, said means comprising a threaded boss on the end of the barrel, an internally threaded nut engaged with the boss the nut having an aperture through which the needle extends, shoulder means on the needle and a tapered helical spring acting between the nut and the shoulder means to resiliently urge the needle into sealing engagement with the seal.

2. A syringe according to claim 1 wherein a plunger support tube is secured at one end in the needle receiv ing bore and extends through the main bore, said plunger being slidable in said support tube, and the resilient seal is disposed in the needle receiving bore between the end of the support tube and the end of the needle.

3. A syringe comprising a barrel, a main bore in the barrel opening at one end thereof, a needle receiving bore in the other end of the barrel substantially coaxial with the main bore and communicating therewith, a hollow needle removably engaged in the needle receiving bore, a syringe plunger extending through the main bore and the needle receiving bore to precisely engage within the hollow needle, sealing means in said needle receiving bore and including a resilient seal through which the plunger slidably moves, and means holding the needle in the needle receiving bore with the inner end of the needle in sealing engagement with said resilient seal said means comprising a threaded boss on the end of the barrel, an internally threaded nut engaged with the boss the nut having an aperture through which the needle extends, shoulder means on the needle and resilient means acting between the nut and the shoulder means to resiliently urge the needle into sealing engagement with the seal, and secured to an operating button on the outer end of the plunger slidable in the main bore, the inner end of the sleeve engaging with the inner end of the main bore when the plunger 6 reaches the limit of its movement in the needle. and volume indicating graduations on the barrel corresponding to axial positions of the sleeve which result in predetermined volumetric capacities of the needle.

4. A syringe comprising a barrel. a main bore in the barrel opening at one end thereof, a needle receiving bore in the other end ot'the barrel and an intermediate bore between the main bore and the needle receiving bore and coaxial therewith. the intermediate bore being of a diameter less than the diameter of both the main and needle receiving bores, a hollow needle in the needle receiving bore. a syringe plunger extending through the main bore to engage within the hollow nee dle. the plunger having an inner section of a diameter to slidably engage the main bore and an outer section of a diameter to engage closely within the needle and the intermediate bore, a resilient. annular seal in the needle receiving bore between the inner end of the needle and the inner end of the bore, and fastening means including a coil spring surrounding the needle and engaged with shoulder means on the needle and applying an axial force to urge resiliently the inner end of the needle into sealing engagement with the seal and compressing the seal against the inner end of the needle receiving bore.

5. A syringe according to claim 4 wherein the needle has a probiscus of a diameter less than that of the inner end portion of the needle into which the plunger slidably moves.

6. A syringe according to claim 4 wherein a repetitive delivery assembly is mounted on the barrel and connected to the plunger, the assembly including a member adjustably clamped to the outer surface of the barrel, elongated rod means extending through a hole in the member parallel with the axis of the main bore, means connecting the outer end of the rod means to the plunger for axial movement therewith, and shoulder means on the other end of the rod means engageable with the member to limit outward movement of the plunger wherein the barrel has volume indicating graduations on its outer surface corresponding to axial positions of the plunger for various volumetric capacities of the syringe.

7. A syringe according to claim 6 wherein the barrel has volume indicating graduations on its outer surface corresponding to axial positions of the plunger for various volumetric capacities of the syringe. 

1. A syringe comprising a barrel, a main bore in the barrel opening at one end thereof, a needle receiving bore in the other end of the barrel substantially coaxial with the main bore and communicating therewith, a hollow needle removably engaged in the needle receiving bore, a syringe plunger extending through the main bore and the needle receiving bore to precisely engage within the hollow needle, sealing means in said needle receiving bore and including a resilient seal through which the plunger slidably moves, and means holding the needle in the needle receiving bore with the inner end of the needle in sealing engagement with said resilient seal, said means comprising a threaded boss on the end of the barrel, an internally threaded nut engaged with the boss the nut having an aperture through which the needle extends, shoulder means on the needle and a tapered helical spring acting between the nut and the shoulder means to resiliently urge the needle into sealing engagement with the seal.
 2. A syringe according to claim 1 wherein a plunger support tube is secured at one end in the needle receiving bore and extends through the main bore, said plunger being slidable in said support tube, and the resilient seal is disposed in the needle receiving bore between the end of the support tube And the end of the needle.
 3. A syringe comprising a barrel, a main bore in the barrel opening at one end thereof, a needle receiving bore in the other end of the barrel substantially coaxial with the main bore and communicating therewith, a hollow needle removably engaged in the needle receiving bore, a syringe plunger extending through the main bore and the needle receiving bore to precisely engage within the hollow needle, sealing means in said needle receiving bore and including a resilient seal through which the plunger slidably moves, and means holding the needle in the needle receiving bore with the inner end of the needle in sealing engagement with said resilient seal said means comprising a threaded boss on the end of the barrel, an internally threaded nut engaged with the boss the nut having an aperture through which the needle extends, shoulder means on the needle and resilient means acting between the nut and the shoulder means to resiliently urge the needle into sealing engagement with the seal, and secured to an operating button on the outer end of the plunger slidable in the main bore, the inner end of the sleeve engaging with the inner end of the main bore when the plunger reaches the limit of its movement in the needle, and volume indicating graduations on the barrel corresponding to axial positions of the sleeve which result in predetermined volumetric capacities of the needle.
 4. A syringe comprising a barrel, a main bore in the barrel opening at one end thereof, a needle receiving bore in the other end of the barrel and an intermediate bore between the main bore and the needle receiving bore and coaxial therewith, the intermediate bore being of a diameter less than the diameter of both the main and needle receiving bores, a hollow needle in the needle receiving bore, a syringe plunger extending through the main bore to engage within the hollow needle, the plunger having an inner section of a diameter to slidably engage the main bore and an outer section of a diameter to engage closely within the needle and the intermediate bore, a resilient, annular seal in the needle receiving bore between the inner end of the needle and the inner end of the bore, and fastening means including a coil spring surrounding the needle and engaged with shoulder means on the needle and applying an axial force to urge resiliently the inner end of the needle into sealing engagement with the seal and compressing the seal against the inner end of the needle receiving bore.
 5. A syringe according to claim 4 wherein the needle has a probiscus of a diameter less than that of the inner end portion of the needle into which the plunger slidably moves.
 6. A syringe according to claim 4 wherein a repetitive delivery assembly is mounted on the barrel and connected to the plunger, the assembly including a member adjustably clamped to the outer surface of the barrel, elongated rod means extending through a hole in the member parallel with the axis of the main bore, means connecting the outer end of the rod means to the plunger for axial movement therewith, and shoulder means on the other end of the rod means engageable with the member to limit outward movement of the plunger wherein the barrel has volume indicating graduations on its outer surface corresponding to axial positions of the plunger for various volumetric capacities of the syringe.
 7. A syringe according to claim 6 wherein the barrel has volume indicating graduations on its outer surface corresponding to axial positions of the plunger for various volumetric capacities of the syringe. 